Dim-To-Off; Soft-Start - Infineon ILD8150 Operation, Design Manual And Performance

ILD8150 80 V high side buck LED driver IC with hybrid dimming
Circuit description
2.2.4

Dim-to-off

ILD8150 turns the output stage off when the PWM dimming input signal duty cycle is less than
D , and on when the PWM dimming input signal duty cycle is higher than D
PWM_IN,OFF
The dim-to-off hysteretic algorithm helps to avoid unstable states at the on/off boundary.
Dim-to-off
Figure 7
2.2.5

Soft-start

Soft-start helps to reduce component stress when the application starts. It further reduces under-shoot of the
input voltage. The soft-start is digitally preset at t
the undimmed condition and up to 10*T
also be set by a microcontroller independently of the preset soft-start. The soft-start process is shown in Figure
8. The number of current steps may vary depending on the actual and previous dimming level.
I [A]
OUT
I
LED,AVG,TARG
I
LED,AVG,2
I
LED,AVG,1
Soft-start
Figure 8
Application Note
100 x I /I
out ref
[%]
0.5
0
D
PWM _IN ,OFF
D
PWM _IN ,ON
SS,100 percent
in the dimmed condition where T
dim
0.025
t
ss
0.5
, defined as the maximum time to reach full light, in
0.025
7 of 28
, as shown in Figure 7.
PWM_IN,ON
D
PWM _IN
[%]
= 1/f . Start-up time may
dim DIM_input
V 1.0
2019-01-23